Bus bar module

ABSTRACT

A bus bar module ( 10 ) includes a bus bar ( 11 ) made of a metal material integrally molded into an insulating layer ( 12 ) made from resin. The bus bar module ( 10 ) also includes a distortion absorptive section ( 15 ) for absorbing distortion resulting from difference in the thermal expansion coefficient between the bus bar ( 11 ) and the insulating layer ( 12 ). Thus, the insulating layer ( 12 ) can stretch out by a difference in expanded dimension between the insulating layer ( 12 ) and the bus bar ( 11 ) at thermal expansion. In this way, the distortion resulting from the difference in the thermal expansion coefficient between the bus bar ( 11 ) and the insulating layer ( 12 ) can be absorbed, and crack occurrence in the insulating layer ( 12 ) can be prevented.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a bus bar module integrallycomposed of bus bar and resin insulating layer.

[0003] 2. Description of the Related Art

[0004] Electric circuits used in an internal combustion engine and inother high temperature environments utilize a bus bar module. A bus barmodule has a plurality of bus bars made of a metallic material that hashigh heat resisting properties (a copper alloy, for example). The busbars are aligned in parallel, and a plurality of bus bars are integratedby means of insert molding with insulating layers made of resin material(epoxy resin, for example) having heat resisting properties. Thus, theinsulating layers insulate the space between the individual bus bars. Abus bar module as described above, is disclosed in the JapaneseUnexamined Patent Publication No. 2000-151149.

[0005] The thermal expansion coefficient of metal generally differswidely from the thermal expansion coefficient of resin. Thus, there is afear that repeated cycling from room temperature conditions to hightemperature conditions may cause cracks in the resin of a bus bar modulethat has a metallic bus bar integrated into a resin insulating layer dueto the differences of the thermal expansion coefficients.

[0006] Accordingly, in view of the aforementioned circumstances, thepresent invention is originated and the subject of the present inventionis to prevent the occurrence of the crack in the resin insulating layer.

SUMMARY OF THE INVENTION

[0007] The present invention relates to a bus bar module with a bus barmade of a conductive metallic material and an integrally molded resininsulating layer. The bus bar module further includes a distortionabsorptive means for absorbing a distortion that results from adifference in thermal expansion coefficients between the bus bar andinsulating layer.

[0008] The distortion absorptive means preferably is disposed to dividethe insulating layer at an appropriate position along the longitudinaldirection of the bus bar.

[0009] The bus bar module preferably comprises an insulating layer onthe surface of the bus bar.

[0010] The distortion absorptive means absorbs the distortion thatresults from a difference in thermal expansion coefficient between thebus bar and the insulating layer. Accordingly, it is possible to preventcracks from occurring in the insulating layer.

[0011] The thermal expansion coefficient of resin is greater than thethermal expansion coefficient of metal. However, the distortionabsorptive means at the divided position of the resin layer effectivelyenables the resin layer to stretch further by the difference in thethermally expanded dimension between the insulating layer and the busbar. Hence, there would be no possibilities for a forceful deformationand an excessive stress upon the insulating layer.

[0012] The bus bar is partially exposed at the divided position of theinsulating layer. However, since the surface of the exposed part iscovered with an insulating coating, the bus bar can be maintained in aninsulating condition.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 illustrates a schematic diagram showing a condition in useof a bus bar module in the embodiment 1.

[0014]FIG. 2 illustrates a partially enlarged sectional view of a busbar module.

[0015]FIG. 3 illustrates a partially enlarged sectional view of a busbar module in the embodiment 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0016] A bus bar module in accordance with the invention is identifiedby the number 10 in Figd. 1 and 2. The bus bar module 10 has a base partmade of synthetic resin material having heat resisting properties andoil resisting properties. The base part is connected to a connector 20that is contained, for example, in a cylinder head 21 of internalcombustion engine. Accordingly, a portion of the connector 20 in theinside of the cylinder head 21 is exposed to a high temperature and alsois smeared with dispersing oil. The bus bar module 10 is led outside ofthe cylinder head 21, and an electrical wiring system 22 is connectedwith an individual bus bar 11 at an edge of the bus bar module 10. Thebus bar module 10 is arranged in an arrangement space 23 that is closeto the cylinder head 21, and accordingly the bus bar module 10 isexposed to a high temperature condition (140° C., for instance) due toheat radiation from the cylinder head 21 during operation of theinternal combustion engine and a normal temperature condition during thecooling down that occurs when the internal combustion engine is stopped.These extreme ranges of temperature conditions are repeated alternately.

[0017] The bus bar module 10 is integrated in one package by means ofintegral insert molding. The bus bar module 10 is composed of aplurality of bus bars 11 made up of metallic materials having electricalconductive properties, such as yellow brass and an alloy of heatresisting copper. Three bus bars 11 are shown in the illustratedembodiments, but two or more than three also may be provided. the busbar module 10 also includes an insulating layer 12 made from a syntheticresin material having heat resisting properties, such as epoxy resin orpolyphenylene sulfide (PPS).

[0018] Each bus bar 11 comprises a main part 11A that stretches in astraight line. A first linking part 11B extends nearly vertically from abase of the main part 11A and is connected to a connector 20. A secondlinking part 11C extends nearly vertically from an edge of the main part11A and is connected to a an electrical wiring system 22. The lengths ofthe main parts 11A of the individual bus bars 11 are different from eachother. Accordingly, the individual linking parts 11B with the connector20 are mutually parallel, and in addition, the individual linking parts11C with the electrical wiring system 22 are also mutually parallel.

[0019] The main parts 11A of the bus bars 11 are parallel and theinsulating layer 12 is between the neighboring main parts 11A. Theinsulating layer 12 also is arranged outside the outermost main parts11A. More particularly, the insulating layer 12 and the main part 11Aare superimposed alternately. Furthermore, an insulating coating 13 withheat resisting properties, such as enamel coating, is provided on theentire surface of each individual bus bar 11. This insulating coating 13is provided on the bus bar 11 prior to insert molding, and hence beforethe bus bar 11 is integrated in one package with the insulating layer12.

[0020] The bus bar module 10 is provided with distortion absorptivemeans 14 that can absorb distortion attributable to thermal expansionresulting from the difference between the thermal expansion coefficientof the metal, which is the material for the bus bar 11, and the thermalexpansion coefficient of the synthetic resin, which is the material forthe insulating layer 12. The distortion absorptive means 14 divides theinsulating layer 12 at a plural number of appropriate positions along alongitudinal direction of the main part 11A of the bus bar 11. In otherwords, the insulating layer 12 is partially removed. The distortionabsorptive means 14 divides the insulating layer 12 into a plurality ofseparated insulating layers 12A along the longitudinal direction of themain part 11A, and a dividing space 15 is maintained between the mutualend faces of the separated insulating layers 12A. The dimension in thelongitudinal direction of the dividing space 15 is established based onthe thermal expansion coefficient of the metal, which is the materialfor the bus bar 11, the thermal expansion coefficient of the syntheticresin, which is the material for the insulating layer 12, thelongitudinal dimension of the individual separated insulating layer 12A,and so on. The established dimension of the dividing space 15 should begreater than the difference in a dimension between the thermallyexpanded dimension of the bus bar 11 and the thermally expandeddimension of the separated insulating layers 12A when the bus bar module10 is heated up to the estimated maximum temperature. Additionally,based on the established dimension of the dividing space, theneighboring separated insulating layers 12A are designed not tointerfere with each other at thermal expansion. In this case, thesurface of the exposed section of the main part 11A in the dividingspace 15 between the separated insulating layers 12A is maintained withthe insulating coating 13.

[0021] The thermal expansion coefficient of synthetic resin iscomparatively greater than that of metal. Accordingly, the elongationamount of the separated insulating layers 12A made from synthetic resinis comparatively greater than the elongation amount of the correspondingregion in the main part 11A of the bus bar 11 made of metal. However, atthe dividing space 15 between the insulating layers 12, the end parts ofthe separated insulating layers 12A can relatively stretch out to themain part 11A for accommodating the difference of the expansiondimension between the bus bar 11 and the separated insulating layers12A. Accordingly, it is not possible to give rise to a forcefuldeformation and an excessive stress upon the separated insulating layer12A.

[0022] The distortion absorptive means 14 can absorb distortion thatresults from the difference in thermal expansion coefficient between themetal of the bus bar 11 and the thermal expansion coefficient of thesynthetic resin of the insulating layer 12. Accordingly, it is possibleto prevent cracks from occurring in the insulating layer 12.

[0023] Additionally, the insulating coating 13 is provided on thesurface of the bus bar 11. As a result, surfaces of the partiallyexposed sections of the main part 11A in the divided position of theinsulating layer 12 are covered the insulating coating 13. Accordingly,an insulating condition can be maintained.

[0024] A bus bar module in accordance with a second embodiment of theinvention is identified by the numeral 30 in FIG. 3. The bus bar module30 has a distortion absorptive means 33 is different from the distortionabsorptive means of the first embodiment. Since the other composition isidentical to the first embodiment, the same numerals are put for thesame composition, and the explanation regarding the structure, operationand effect is omitted here.

[0025] The distortion absorptive means 33 of the second embodimentcomprises a part 31B of the individual main part 31A of each bus bar 31that is sigmoidally or sinusoidally bent to define a plurality ofS-shapes. The sigmoidally bent parts 31B, are disposed in a selectedlongitudinal position along the bus bars 31, and define curvatures thatare the same among the neighboring main parts 31A. Accordingly, the bentparts 31B effectively nest with one another, and the thickness of theinsulating layer 32A between the neighboring main parts 31A, as measuredin the top-to-bottom direction of FIG. 3, is continuously uniform alongthe longitudinal direction. In addition, the outside surface of theinsulating layer 32B outside the main part 31A is flat and parallel tothe longitudinal direction of the bus bar 31. Therefore, the thicknessof the region corresponding to the sigmoidally bent part 31B of theinsulating layer 32B is uniform in the longitudinal direction.

What is claimed is:
 1. A bus bar module (10; 30); wherein at least onebus bar (11; 31) made of a conductive metallic material and a resininsulating layer (12; 32A) are integrally molded, whereby a distortionabsorptive means (15; 33) is provided allowing a distortion to beabsorbed that results from a difference in thermal expansioncoefficients between the bus bar (11; 30) and insulating layer (12;32A).
 2. The bus bar module of claim 1, wherein the distortionabsorptive means (15; 33) divides the insulating layer (12; 32A) at aselected longitudinal position along the bus bar (11; 30).
 3. The busbar module of claim 2, further comprising an insulating coating (33)covering the bus bar (11; 30).
 4. A bus bar module (10; 30) comprising:a plurality of bus bars (11; 31) formed from a metallic material, eachsaid bus bar (11; 31) having a main section (11A; 31A), said mainsections (11A; 31A) of said bus bars (11; 31) being substantiallyparallel to one another; an insulating layer (12; 32) formed from aresin material and surrounding at least portions of said main sections(11A; 31A) of said bus bars (11; 31);and a distortion absorptive means(15; 33) for compensating for differences in thermal expansioncharacteristics of said bus bars (11; 31) and said insulating layer (12;32).
 5. The bus bar module (10) of claim 4, wherein said insulatinglayer (12) comprises first and second insulating layers (12A)surrounding first and second portions of said main section (11A) of eachsaid bus bar (11), said distortion absorptive means (15) comprises adividing space between said first and second first and second insulatinglayers (12A).
 6. The bus bar module (10) of claim 4, wherein saiddistortion absorption means (33) comprises at least one curved section(31A) in each said bus bar (31).
 7. A bus bar module (10) comprising: aplurality of bus bars (11) formed from a metallic material, each saidbus bar (11) having a main section (11A), said main sections (11A) ofsaid bus bars (11) being substantially parallel to one another, a firstinsulating layer (12A) formed from a resin material and surrounding afirst portion of each said main section (11A) of each said bus bar (11),and a second insulating layer (12A) formed from a resin material andsurrounding a second portion of each said main section (11A) of eachsaid bus bar (11), said first and second insulating layers (12A) beingspaced from one another by a dividing space (15) such that each said busbar (11) includes a portion in said dividing space (15) that is notsurrounded by either of said first and second insulating layers (12A),said dividing space (15) being dimensioned to accommodate thermalexpansion of said first and second insulating layers (12A).
 8. The busbar module (10) of claim 7, further comprising an insulating coating(13) surrounding all of each said main section (11A) of each said busbar (11).
 9. The bus bar module (10) of claim 7, wherein the mainsections (11A) of the bus bars (11) are insert molded into theinsulating layers (12A), such that the resin material of the insulatinglayers (12A) defines a unitary matrix of resin material surrounding andengaging the main sections (11A) of the bus bars (11).
 10. A bus barmodule (30) comprising a plurality of substantially parallel bus bars(31) formed from a metallic material, each said bus bar (31) having twospaced apart linear sections (31A) and a curved section (31B), saidcurved sections (31B) being substantially aligned with one another, saidbus bar module (30) further comprising an insulating coating (32) formeda resin material surrounding both the linear sections (31A) and thecurved sections (31B) of the bus bars (31).
 11. The bus bar module (30)of claim 10, wherein, the curved section (31B) comprises a plurality ofsubstantially S-shaped curves.
 12. The bus bar module (30) of claim 10,wherein the bus bars (31) are insert molded into the insulating coating(32), such that the insulating coating (32) defines a unitary matrix ofresin material surrounding the bus bars (31).